TBM 刀具设计中围岩力学参数的选择

 围岩力学特性是隧道掘进机———TBM 刀具设计中必须考虑的重要因素, 而且这一因素也直接关系到TBM 的总体设计及选用TBM 施工的可行性。选择以单轴抗压强度为核心的参数系统作为刀具设计依据是不完善的。TBM掘进过程中, 刀具正下方因承受纵向压力而下陷, 刀具两侧附近岩石由于受到平行掌子面的挤压而隆起。岩石下陷和隆起的同时, 其内部出现张性或张剪性破裂面。当相临刀具诱发的隆起区重叠时, 岩石便以碎块的形式脱离掌子面。在刀具荷载作用下, 掌子面上两点之间的相对位移越大, 对掘进越有利, 而不同点之间的相对位移受岩石泊松比μ和弹性模量E 的控制。较大的μ、较小的E 对TBM掘进是有利的。除了单轴抗压强度外, 刀具设计还应综合考虑变形参数μ和E 。     

围岩分类在TBM滚刀寿命预测中的应用

预测滚刀寿命,根据刀具磨损规律把握最好的换刀时机对隧道掘进机（TBM）来说是极其重要的.文章以秦岭隧道为例,应用围岩分类来预测刀具消耗量.根据影响TBM掘进率的岩石单轴抗压强度、岩石耐磨性、岩石硬度及岩体节理发育程度对围岩TBM工作条件等级的划分,定性分析了围岩等级与刀具消耗量的关系.在此基础上,提出围岩等级数的概念,得出不同的等级数与其相应的耗刀量之间的定量关系.     

TBM刀具设计中围岩力参数的选择

围岩力学特性是隧道掘进机-TBM刀具设计中必须考虑的重要因素，而且这一因素也直接关系到TBM的总体设计及选用TBM施工的可行性。选择以单轴抗压强度为核心的参数系统作为刀具设计依据是不完善的。TBM掘进过程中，刀具正下主因承受纵向压力而下陷，刀具两侧附近岩石由于受到平行掌子面的挤压而隆起。岩石下陷和隆起的同时，其内部出现张性或张剪性破裂面。当相临刀具诱发的隆起区重叠时，岩石例以碎块的形式脱离掌子面。在刀具荷载作用下，掌子面上两点之间的相对位移越大，对掘进越有利，而不同点之间的相对位移受岩石泊松比μ和弹性模量E的控制。较大的μ、较小的E对TBM掘进是有利的。除了单轴抗压强度外，刀具设计还应综合考虑变形参数μ和E。     

斜井TBM刀具磨损更换预测方法研究

TBM掘进隧道过程中不可避免地遇到刀具磨损问题,合理有效的换刀时机对减少换刀次数、保证施工的连续和正常进行具有重要意义。以补连塔煤矿斜井TBM工程为背景,提出了基于TBM总推力和总扭矩的掘进速度判别法来预测刀具磨损的更换时机。经实践表明,依据掘进速度来预测刀具磨损情况简单可行。     

基于盾构掘进参数的岩石可切割性模糊识别

 基于重庆越江隧道盾构掘进参数和模糊识别原理,对岩石的可切割性进行研究。对典型泥岩和砂岩进行现场点荷载强度试验,利用数据采集、存储系统,获取与典型泥岩和砂岩相应的盾构刀盘推力及掘进速率,并运用多元回归分析方法建立典型泥岩和砂岩地层下的盾构掘进速率预测模型,并构建盾构掘进速率特性空间,依据岩性对空间进行划分,用掘进速率表征相应岩石的可切割性。将样本岩石的掘进速率与典型岩石的掘进速率之差定义为距离,利用模糊识别原理,建立掘进速率与归一化距离的对应关系,获得样本岩石掘进速率对典型岩石的掘进速率的隶属度,从而建立岩石可切割性识别函数。重庆越江隧道沿线围岩以泥岩、砂岩及泥岩夹砂岩交互变化为特征,属于软岩～中硬岩系列,岩石软硬变化范围不是很大。因此,将岩石可切割性划分为软、中软及中硬三个级别,对掘进过程中岩石的可切割性进行识别。识别结果是隧道施工阶段工程地质勘察报告的有益补充,增强了盾构掘进控制的科学性和准确性,为预测刀具磨损和确定换刀时机提供了科学的参考依据。     

不同围压条件下TBM刀具破岩模式的数值研究

为了研究不同围压条件下TBM刀具在掘进施工过程中的破岩机理,基于2-D离散单元法,利用UDEC仿真软件建立了双把TBM刀具侵入岩石的仿真模型。在此基础上设计了一组数值试验,成功地模拟出了不同围压条件以及不同刀间距下岩石裂纹生成,扩展和岩石破碎的全过程。仿真结果表明：TBM刀具作用下岩石存在四种基本的破碎模式,它们的出现与围压以及刀间距有关;破碎模式对刀具的破岩效率,岩石破碎块度均有影响;随着围压的增加,最优刀间距增大,但围压超过一定值后,最优刀间距反而减小。     

高地应力作用下大理岩岩体的TBM掘进试验研究

滚刀破岩效率的研究主要集中在室内线性试验机破岩试验和数值分析2个方面,在工地开展TBM掘进试验尚不普遍。锦屏二级水电站采用3台TBM开挖隧道群,3台TBM在不同洞深(不同地应力)条件对大理岩岩体进行TBM掘进试验、岩石渣片筛分试验及大渣片统计分析,研究岩体条件、TBM机器参数、TBM运行参数对TBM掘进速度的影响及高地应力作用下岩体可掘性指数的变化。研究结果表明:在高地应力条件下,尽管TBM掘进速度随推力增加而增大,但推力超过一定值后,TBM并不在优化状态下运行,TBM的运行需与岩体条件及地应力条件相匹配。     

全断面硬岩盾构掘进参数与刀具磨损规律分析

通过对PN 9.13m TBM/土压双模式盾构在全断面硬岩中掘进参数与刀具磨损规律的分析,分别讨论了在全断面硬岩中掘进参数的变化规律、盾构掘进出渣情况以及刀具的磨损原因,提出了依据掘进参数和掘进出碴情况来判定土压平衡模式中刀具的磨损状况的方法、并验证了其可行性.研究结果表明:掘进参数在盾构掘进过程中可较准确反映刀具磨损情况,并通过掘进中出渣、掘进速度稳定性等的现象反馈进一步判断掘进参数与刀具的磨损状态.该研究结果可在盾构施工中对刀具进行有效保护,减少换刀频率、降低工程成本、减少停机时间、提高掘进效率,对指导相应施工具有一定的工程意义.     

基于TBM掘进性能的岩体分级及可掘性等级感知识别方法

传统的围岩分级方法难以适用于TBM掘进性能评价和预测,因此,建立一套适用于TBM施工的岩体可掘性分级系统并实现可掘性等级的准确感知识别。基于4条TBM隧道的152组岩体和机器数据建立的数据库,分析岩体参数与TBM可掘性评价指标的相关性,采用多目标决策方法 TOPSIS实现TBM隧道岩体可掘性分级。由于实际TBM掘进中岩体参数较难获取,利用单刀推力(Th)、净掘进速度(PR)、刀盘转速(RPM)以及贯入度(PRev)等TBM掘进参数对所提出的岩体可掘进性等级进行了感知识别。感知识别中,采用贝叶斯优化确定多种机器学习分类算法的最优超参数组合,实现最大感知识别准确率,比较不同算法对于岩体可掘性等级感知识别的适用性,并确定最优的感知识别方法。最后,基于吉林引松工程的实时TBM掘进数据,验证岩体可掘性分级及可掘性等级感知识别方法的有效性和准确性。研究成果可用于TBM平稳运行段岩体可掘性评估预测,为掘进参数优化和建立TBM智能化控制系统提供参考。     

盾构连续移动式冲击凿岩技术试验研究

TBM设备在硬岩掘进时,存在工作效率低下、滚刀磨损严重以及工作机构耗损严重等缺陷。严重降低了掘进效率,影响整机的性能。为了更加适应地层的开挖,通过对原有开挖刀盘进行分析,研究一种连续移动式冲击凿岩开挖技术。通过仿真分析法,对不同钻头落点位置模拟仿真,并通过试验法搭建试验平台,对气动潜孔锤和液压凿岩机分别进行试验,以验证凿岩能力。试验表明,连续移动冲击凿岩设备中,液压凿岩机比气动潜孔锤效果更明显,且方案具备可行性。利用TBM刀盘结合冲击破岩装置,可以使岩石单向受压,使岩石更容易破碎,先利用冲击形成预裂或临空面,再利用滚刀压裂,可有效提高掘进效率,并且减少了盾构施工过程中刀盘上的刀具磨损情况,增强了TBM设备在面对硬岩掘进的过程中对硬质地层的切削能力,可以有效地提高掘进设备对地层的适应性。     

Study on rock mass boreability by TBM penetration test under different in situ stress conditions

Rock mass boreability is a comprehensive parameter reflecting the interaction between rock mass and a tunnel boring machine (TBM). Many factors including rock mass conditions, TBM specifications and operation parameters influence rock mass boreability. In situ stress, as one of the important properties of rock mass conditions, has not been studied specifically for rock mass boreability in TBM tunneling. In this study, three sets of TBM penetration tests are conducted with different in situ stress conditions in three TBM tunnels of the Jinping II Hydropower Station. The correlation between TBM operation parameters collected during the tests and the rock mass boreability index is analyzed to reveal the influence of in situ stress on rock mass boreability and TBM excavation process. The muck produced by each test step is collected and analyzed by the muck sieve test. The results show that in situ stress not only influences the rock mass boreability but also the rock fragmentation process under TBM cutters. If the in situ stress is high enough to cause the stress-induced failure at the tunnel face, it facilitates rock fragmentation by TBM cutters and the corresponding rock boreability index decreases. Otherwise, the in situ stress restrains rock fragmentation by TBM cutters and the rock mass boreablity index increases. Through comparison of the boreability index predicted by the Rock Mass Characteristics (RMC) prediction model with the boreability index calculated from the penetration test results, the influence degree of different in situ stresses for rock mass boreability is obtained.     

In situ TBM penetration tests and rock mass boreability analysis in hard rock tunnels

Boreability is popularly adopted to express the ease or difficulty with which a rock mass can be penetrated by a tunnel boring machine. Because the boreability is related to the rock mass properties, TBM specifications and TBM operation parameters, an accurately definable quantity has not been obtained so far. In order to analyze and compare rock mass boreability, a series of TBM shield friction tests were conducted in a TBM tunneling site. Two sets of TBM penetration tests were performed in different rock mass conditions during tunneling in rock. In each step of the penetration test, the rock muck was collected to perform the muck sieve analyses and the shape of large chips was surveyed in order to analyze the TBM chipping efficiency under different cutter thrusts. The results showed that a critical point exists in the penetration curves. The penetration per revolution increases rapidly with increasing thrust per cutter when it is higher than the critical value. The muck sieve analysis results verified that with increasing thrust force, the muck size increases and the rock breakage efficiency also increases. When the thrust is greater than the critical value, the muck becomes well-graded. The muck shape analysis results also showed with the increase of the thrust, the chip shape changes from flat to elongated and flat. The boreability index at the critical point of penetration of 1 mm/rev. defined as the specific rock mass boreability index is proposed to evaluate rock mass boreability.     

A new hard rock TBM performance prediction model for project planning

Among the models used for performance prediction of hard rock tunnel boring machines two stand out and are often used in the industry. They include the semi theoretical model by Colorado School of Mines and the empirical model by Norwegian University of Science and Technology in Trondheim (NTNU). While each have their strong points and area of applications, more accurate prediction has been sought by modifying one of the existing models or introduction of a new model. To achieve this, a database of actual machine performance from different hard rock TBM tunneling projects has been compiled and analyzed to develop a new TBM performance prediction model. To analyze the available data and offer new equations using statistical methods, relationships between different geological and TBM operational parameters were investigated. Results of analyzes show that there are strong relationships between geological parameters (like UCS, joint spacing and RQD) and TBM performance parameters specially Field Penetration Index (FPI). In this study, a boreability classification system and a new empirical chart, for preliminary estimation of rock mass boreability and TBM performance is suggested.     

Development of a rock mass characteristics model for TBM penetration rate prediction

The TBM tunneling process in hard rock is actually a rock or rock mass breakage process, which determines the efficiency of tunnel boring machine (TBM). On the basis of the rock breakage process, a rock mass conceptual model that identifies the effect of rock mass properties on TBM penetration rate is proposed. During the construction of T05 and T06 tunnels of DTSS project in Singapore, a comprehensive program was performed to obtain the relevant rock mass properties and TBM performance data. A database, including rock mass properties, TBM specifications and the corresponding TBM performance, was established. Combining the rock mass conceptual model for evaluating rock mass boreability with the established database, a statistical prediction model of TBM penetration rate is set up by performing a nonlinear regression analysis. The parametric studies of the new model showed that the rock uniaxial compressive strength and the volumetric joint count have predominantly effects on the penetration rate. These results showed good agreement with the numerical simulations. The model limitations were also discussed.     

Real-time rock mass condition prediction with TBM tunneling big data using a novel rock–machine mutual feedback perception method

Real-time perception of rock mass information is of great importance to efficient tunneling and hazard prevention in tunnel boring machines (TBMs). In this study, a TBM–rock mutual feedback perception method based on data mining (DM) is proposed, which takes 10 tunneling parameters related to surrounding rock conditions as input features. For implementation, first, the database of TBM tunneling parameters was established, in which 10,807 tunneling cycles from the Songhua River water conveyance tunnel were accommodated. Then, the spectral clustering (SC) algorithm based on graph theory was introduced to cluster the TBM tunneling data. According to the clustering results and rock mass boreability index, the rock mass conditions were classified into four classes, and the reasonable distribution intervals of the main tunneling parameters corresponding to each class were presented. Meanwhile, based on the deep neural network (DNN), the real-time prediction model regarding different rock conditions was established. Finally, the rationality and adaptability of the proposed method were validated via analyzing the tunneling specific energy, feature importance, and training dataset size. The proposed TBM–rock mutual feedback perception method enables the automatic identification of rock mass conditions and the dynamic adjustment of tunneling parameters during TBM driving. Furthermore, in terms of the prediction performance, the method can predict the rock mass conditions ahead of the tunnel face in real time more accurately than the traditional machine learning prediction methods.     

TBM自重对围岩变形影响的数值模拟研究

为研究双护盾全断面隧道掘进机(TBM)自重对围岩变形的影响,基于FLAC3D有限差分软件,通过改变隧道的埋深与围岩条件,建立3种工况数值模型,并对每个工况分别进行了考虑TBM自重与不考虑其自重的数值模拟,以对比各种工况下有无TBM自重作用的隧道围岩纵向位移曲线(LDP曲线);研究了TBM自重对围岩变形的影响。模拟结果表明,TBM自重可抑制隧道围岩的径向位移,并随着开挖隧道的围岩等级升高、埋深变浅,其自重对围岩变形的影响越大,且与不考虑TBM自重的围岩变形相比,边墙洞壁的径向位移减小率最大,仰拱与拱顶次之。这些认识对研究TBM与围岩的相互作用和预测卡机有重要意义。     

Correlation of rock cutting tests with field performance of a TBM in a highly fractured rock formation: A case study in Kozyatagi-Kadikoy metro tunnel,Turkey

This paper presents and discusses detailed field and laboratory studies concerning boreability prediction of tunnel boring machines (TBMs) used in Kozyatagi-Kadikoy metro tunnels in Istanbul in a highly fractured rock formation. The determination of some design parameters and performance prediction of a tunnel boring machine (TBM) are carried out using full-scale rock cutting test. The intact rock samples having minimum sizes of 1.0 × 0.7 × 0.7 m are obtained from shale and limestone (Kartal Formation) along the tunnel line. The rock samples are subjected to full-scale laboratory rock cutting tests with different depth of cut and cutter spacing values using a constant cross section (CCS) disc cutter of 330 mm in diameter. Cutter forces, i.e., thrust force, rolling force and specific energy values are recorded for each cut. The results of the tests are first used to calculate TBM design and performance parameters such as torque and thrust requirements and cutting rates. In the second part of the research, the field performance of the TBM is recorded with the aid of data acquisition system installed within TBM and the predicted performance and design values obtained from full-scale rock cutting tests are compared with the field values. It is observed that fractured characteristics of the rock formation affect tremendously TBM performance and predicted values differ from the field data in some extend. It is believed that the results will serve as a guide for efficient selection and use of TBMs.     

Evaluating D&B and TBM tunnelling using NTNU prediction models

Drill and Blast (D&B) and Tunnel Boring Machine (TBM) are the two dominating excavation methods in hard rock tunnelling. Selection of the cost effective excavation method for a tunnel is a function of tunnel cross section area, rock conditions, tunnel length, availability of skilled labour and proper equipment, and project schedule. Over the past few decades, major technological development and technical advances have been achieved in both methods. Yet, in many tunnelling projects, choosing the excavation method is still a challenge and requires considering pros and cons of each method and estimating construction time, costs, as well as post construction and operation & maintenance, and related risk in the planning phase. In this study, the productivity and efficiency of the D&B and TBM options for excavating certain size tunnels have been examined. The analysis is based on recent NTNU prediction models for advance rate and unit excavation cost for given ground conditions and tunnel geometry. For excavation of large size tunnels in very hard rock, the D&B method seems to be the cost effective choice irrespective to tunnel geometry. This is compared to smaller long tunnels with good boreability were the TBM has higher advance rate. The tunnel size and rock conditions have higher impact on the TBM performance and costs than for D&B. This refers to lower risk of using D&B where the use of this method is otherwise justified.     

锦屏二级水电站引水隧洞TBM开挖方案对岩爆风险影响研究

 为了提高施工效率,降低现场施工人员和设备的风险,锦屏二级水电站1#、3#引水隧洞采用大断面TBM进行施工。超大埋深TBM全断面施工,对于等级较强的岩爆,仍然可能会给TBM设备带来一定伤害。为此,通过微震实时监测和数值分析等手段,开展了TBM施工速度、导洞施工等TBM开挖方案对岩爆风险的影响研究。结果表明,降低TBM施工速率,有利于降低岩爆发生的风险;导洞施工+TBM联合施工对于极强岩爆风险的防范是十分有利的。研究成果可为TBM安全快速掘进提供重要的参考价值,也将为其他工程提供借鉴,具有重要的工程价值。